Contact dermatitis is a red, itchy rash caused by a substance that comes into contact with your skin. The rash isn't contagious or life-threatening, but it can be very uncomfortable.

Possible causes include soaps, cosmetics, fragrances, jewelry, and plants, such as poison ivy or poison oak. Some people are exposed to substances at work that may cause contact dermatitis.

To treat contact dermatitis successfully, you need to identify and avoid the cause of your reaction. If you can avoid the offending substance, the rash usually clears up in two to four weeks. You can try soothing your skin with cool, wet compresses, anti-itch creams and other self-care steps.

Contact dermatitis usually occurs on areas of your body that have been directly exposed to the substance — for example, along a calf that brushed against poison ivy or under a watchband that triggers an allergy. The reaction usually develops within minutes to hours of exposure to an irritating substance or allergen. The rash can last two to four weeks.

Signs and symptoms of contact dermatitis include:

Red rash or bumps

Itching, which may be severe

Dry, cracked, scaly skin, if your condition is chronic

Blisters, draining fluid and crusting, if your reaction is severe

Swelling, burning or tenderness

The severity of the rash depends on:

How long you're exposed

The strength of the substance that caused the rash

Environmental factors, such as temperature, airflow and sweating from wearing gloves

Your genetic makeup, which can affect how you respond to certain substances

When to see a doctor

See your doctor if:

The rash is so uncomfortable that you are losing sleep or are distracted from your daily routine

The rash is painful, severe or widespread

You're embarrassed by the way your skin looks

The rash doesn't get better within a few weeks

The rash affects your face or genitals

Seek immediate medical care in the following situations:

You think your skin is infected — clues include fever and pus oozing from blisters.

Your lungs, eyes or nasal passages are painful and inflamed, perhaps from inhaling an allergen.

You think the rash has damaged the mucous lining of your mouth and digestive tract.

Contact dermatitis is caused by a substance you're exposed to that irritates your skin or triggers an allergic reaction. The substance could be one of thousands of known allergens and irritants. Some of these substances may cause both irritant contact dermatitis and allergic contact dermatitis.

Irritant contact dermatitis is the most common type. This nonallergic inflammatory reaction occurs when a substance damages your skin's outer protective layer.

Some people react to strong irritants after a single exposure. Others may develop signs and symptoms after repeated exposures to even mild irritants. And some people develop a tolerance to the substance over time.

Common irritants include:

Solvents

Rubbing alcohol

Bleach

Personal care products, such as soaps, deodorants and cosmetics

Airborne substances, such as sawdust or wool dust

Burdock, a plant used in alternative medicine therapies

Allergic contact dermatitis occurs when a substance to which you're sensitive (allergen) triggers an immune reaction in your skin. It usually affects only the area that came into contact with the allergen. But it may be triggered by something that enters your body through foods, flavorings, medicine, or medical or dental procedures (systemic contact dermatitis).

You may become sensitized to a strong allergen such as poison ivy after a single exposure. Weaker allergens may require multiple exposures over several years to trigger an allergy. Once you develop an allergy to a substance, even a small amount of it can cause a reaction.

Common allergens include:

Nickel, which is used in jewelry, buckles and many other items

Medications, such as antibiotic creams and oral antihistamines

Balsam of Peru, which is used in many products, such as perfumes, cosmetics, mouth rinses and flavorings

Plants such as poison ivy and mango, which contain a highly allergenic substance called urushiol

Airborne substances, such as from aromatherapy and spray insecticides

Products that cause a reaction when you're in the sun (photoallergic contact dermatitis), such as some sunscreens and oral medications

The rate of allergic contact dermatitis in children is similar to that in adults. Children develop the condition from the usual offenders and also from exposure to car seats, the plastic in toilet seats and infant clothing snaps.

Occupational contact dermatitis refers to rashes resulting from exposure to allergens or irritants on the job. Certain occupations and hobbies put you at higher risk of this type of contact dermatitis. Examples include:

Health care workers and pharmaceutical industry employees

Metalworkers

Construction workers

Hairdressers and cosmetologists

Waiters

Scuba divers or swimmers, due to the rubber in face masks or goggles

Cleaners

Gardeners and agricultural workers

Chefs and others who work with food

Contact dermatitis can lead to the following complications:

Chronic itchy, scaly skin. A skin condition called neurodermatitis (lichen simplex chronicus) starts with a patch of itchy skin. You scratch the area, which makes it even itchier. So you keep scratching. Eventually, you may scratch simply out of habit. This condition can cause the affected skin to become discolored, thick and leathery.

Infection. If you repeatedly scratch a rash, you may cause it to become wet and oozing. This creates a good place for bacteria or fungi to grow and may cause an infection.

You're likely to start by seeing your primary care doctor. He or she might refer you to a doctor who specializes in skin disorders (dermatologist).

Because appointments can be brief, it's a good idea to be well-prepared for your appointment.

What you can do

List your signs and symptoms, including when they began and how long they've lasted.

Avoid any substances that you think may have caused the rash.

Make notes about any new products you've started using and any substances that regularly come in contact with your affected skin areas.

Make a list of all the medications and supplements you take. Even better, take along the original bottles and a list of the dosages and directions. Include any creams or lotions you're using.

List questions to ask your doctor.

For contact dermatitis, some basic questions you could ask your doctor include:

What might be causing my signs and symptoms?

Are tests needed to confirm the diagnosis?

What treatments are available, and which do you recommend?

Is this condition temporary or chronic?

Can I wait to see if the condition goes away on its own?

Will scratching spread the rash?

Will popping the blisters spread the rash?

What skin care routines do you recommend to improve my condition?

How can I prevent this in the future?

What to expect from your doctor

Your doctor is likely to ask you questions such as the following:

When did you begin noticing symptoms?

How often do you have symptoms?

Have your symptoms been continuous or occasional? Do they get better over the weekend or during vacation?

Does anything seem to make your symptoms better or worse?

Have you started using any new cosmetics or household products?

Does your work or a hobby involve using products that often come in contact with your skin?

The key to successful treatment of contact dermatitis is identifying what's causing your symptoms and figuring out whether you have the irritant or allergic type. Doctors rely on these main steps to determine the cause:

A thorough medical history and physical exam. Your doctor may be able to diagnose contact dermatitis and identify its cause by talking to you about your signs and symptoms, questioning you to uncover clues about the culprit, and examining your skin to note the pattern and intensity of your reaction.

A patch test. Your doctor may recommend a patch test (contact delayed hypersensitivity allergy test) to see if you're allergic to something. This test can be useful if the cause of your rash isn't apparent or if your rash recurs often.

You may be asked to avoid certain medications and sun tanning your back for a week or two before the test.

During a patch test, small amounts of potential allergens are applied to adhesive patches, which are then placed on your skin. The patches remain on your skin for two days, during which time you'll need to keep your back dry.

Your doctor then checks for a skin reaction under the patches and determines whether further testing is needed. Often, people react to more than one substance.

Key treatments for contact dermatitis include:

Avoiding the irritant or allergen. The key to this is identifying what's causing your rash and then staying away from it. Your doctor may give you a list of products that typically contain the substance that affects you.

Applying medications to repair the skin. You can help repair the skin and prevent relapse with creams and ointments containing drugs that affect the immune system, such as calcineurin inhibitors tacrolimus (Protopic) or pimecrolimus (Elidel). This solution is recommended for long-term treatment of contact dermatitis. But the Food and Drug Administration has warned about a possible link between these drugs and lymphoma and skin cancer.

Using oral medications. In severe cases, your doctor may prescribe oral corticosteroids to reduce inflammation, antihistamines to relieve itching or antibiotics to fight a bacterial infection.

To help reduce itching and soothe inflamed skin, try these self-care approaches:

Avoid allowing the reaction-causing substance to touch your skin. If it's a piece of jewelry, you may be able to wear it by putting a barrier between you and the metal. For example, line the inside of a bracelet with a piece of clear tape or paint it with clear nail polish.

Protect your hands with moisturizers and gloves. Reapply moisturizers throughout the day. And choose gloves based on what you're protecting your hands from. For example, plastic gloves lined with cotton are good if your hands are often wet.

Some alternative medicine therapies and ingredients are proved to cause contact dermatitis as a side effect. Examples include:

Avoid irritants and allergens. Try to identify and avoid substances that irritate your skin or cause an allergic reaction.

Wash your skin. You might be able to remove most of the rash-causing substance if you wash your skin right away after contacting it. Use a mild, fragrance-free soap and rinse completely. Also wash any clothing or other items that may have come into contact with a plant allergen such as poison ivy.

Wear protective clothing or gloves. Face masks, goggles, gloves and other protective items can shield you from irritating substances, including household cleansers.

Apply an iron-on patch to cover metal fasteners next to your skin. This can help you avoid a reaction to jean snaps, for example.

Apply a barrier cream or gel. These products can provide a protective layer for your skin. For example, an over-the-counter skin cream containing bentoquatam (IvyBlock) may prevent or lessen your skin's reaction to poison ivy.

Use moisturizer. This can help restore your skin's outermost layer and keep your skin supple.

Take care around pets. Pets can easily spread to people allergens from plants such as poison ivy.

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